Lost

One of the most expensive series in television history, Lost's complex mythology and intricate character development fascinated fans for six seasons. Created by JJ Abrams, Damon Lindelof and Jeffrey Lieber, the series debuted to considerable critical fanfare in September 2004, with a large ensemble cast featuring established household names from TV and film including Matthew Fox, Terry O'Quinn, Michelle Rodriguez and Harold Perrineau alongside then-newcomers such as Evangeline Lilly and Ian Somerhalder.

Lost's use of flashbacks, flashforwards, jumps in time and parallel alternate narratives (nicknamed 'flash-sideways' in the show's universe) kept the mysteries coming right the way up until the series finale, which aired in May 2010 to mixed response.